New targeted therapies for breast cancer: A focus on tumor microenvironmental signals and chemoresistant breast cancers

Table 1 Current therapeutics for breast cancer

Drug	Trade name	Class	Anticancer mechanism
Classical chemotherapy
Methotrexate	Abitrexate®, Mexate®, Folex®	Antimetabolites, folate analogs	Folate receptor competitive antagonist[218]
5-fluorouracil	Adrucil®, Efudex®, Fluoroplex®, prodrug capecitabine/Xeloda®	Antimetabolite, pyrimidine analogs	Inhibition of the phosphatase and tensin homolog thymidylate synthase[219]
Gemcitabine hydrochloride	Gemzar®
Doxorubicin hydrochloride	Adriamycin®	Anthracycline	Deoxyribonuclease inhibitor[220]
Epirubicin hydrochloride	Ellence®
Pamidronate disodium	Aredia®	Nitrogen-containing bisphosphonate	Inhibition of farnesyl pyrophosphate synthase activity[221]
Cyclophosphamide	Clafen®, Cytoxan®, Neosar®	Nitrogen mustard alkylating agent	Inhibition of DNA replication by interacting with the alkyl group of DNA guanine base[222]
Paclitaxel	Abraxane® Taxol®	Taxanes	Microtubule Inhibitors[223,224]
Docetaxel	Docecad®, Taxotere®
Ixabepilone	Ixempra®	Epothilone B analog
Targeted therapy
Everolimus	Afinitor®	mTOR inhibitor	Silencing of PI3K/Akt/mTOR signaling[225]
Trastuzumab	Herceptin®	HER2 inhibitor	Anti-HER2 monoclonal antibodies[226,227]
Pertuzumab	Perjeta®
Ado-Trastuzumab Emtansine	Kadcyla®	Antibody-drug conjugate	HER2 inhibitor and cytotoxic agent[228]
Lapatinib ditosylate	Tykerb®	Dual tyrosine kinase inhibitor	EGFR/HER2 inhibitor[229]
Hormone therapy
Toremifene	Fareston®	Selective ER modulator	Silence ER signaling[230,231]
Fulvestrant	Faslodex®	ER antagonists
Tamoxifen citrate	Nolvadex®
Anastrozole	Arimidex®	Aromatase inhibitors	Inhibit estrogen synthesis[232-234]
Exemestane	Aromasin®
Letrozole	Femara®
Goserelin acetate	Zoladex®	GnRH agonist
Megestrol acetate	Megace®	Progesterone derivative	Progestational and antigonadotropic effects[235]

PI3K: Phosphatidylinositol 3-kinase; Akt: Protein kinase B; HER: Epidermal growth factor receptor 2.